Semi Auto vs Full Auto

There seems to be a lot of confusion about what Semi Auto vs Full Auto means when it comes to firearms. Well, below is a diagram explaining it in more detail. You can download a PDF of this diagram here.

Basically, when we’re talking about Semi Auto vs Full Auto, we’re talking about the action of the firearm. The action, put simply, is how a bullet round is fired, ejected and a new round loaded into the firing chamber of a gun. This process is also referred to as “cycling” a firearm. You can read more about those different types of actions in our Glossary of Firearms Terms. In this case, we’re talking about Semi Auto vs Full Auto.

Semi Auto or Semi Automatic means that the action is semi-automatic. What that means is that once you have a round in the firing chamber, when you pull the trigger, that round will fire. As the bullet exits the firearm, the gases expelled from the cartridge eject the spent bullet casing and springs load the next round into the chamber from either an internal or external magazine. That’s it. One trigger pull = one bullet fired. It’s referred to as “semi-automatic” because the round is automatically cycled with a single trigger pull.

With Full Auto or Fully Automatic both the action and the trigger pull creates a fully automatic cycle. This means that once a round is loaded into the chamber, if you pull and hold the trigger, the firearm will continue to fire until you let go of the trigger or run out of ammunition. Fully automatic firearms are sometimes called “machine guns”.

It should be noted, that semi-auto firearms are commercially available in a variety of makes, models and calibers. In the U.S., fully automatic firearms are available only to the military or law enforcement. Individual citizens can only purchase fully automatic firearms after obtaining expensive permits and other documentation as well as passing federal, state and local screening processes. In short, machine guns are not readily available to the public and are difficult to obtain.

So, there is Semi Auto vs Full Auto in a nutshell. See more in the diagram below and the video below that.